Incidental Capture of seabirds by Japanese southern bluefin tuna longline vessels in New Zealand waters, 1988-1992
Summary Fishery observers recorded incidental capture of seabirds during 785 days on Japanese bluefin tuna longline vessels around New Zealand between April and August each year, 1988-1992. High numbers of albatrosses Diomedea spp. and petrels Procellaria spp. were caught on longline hooks during se...
Published in: | Bird Conservation International |
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Format: | Article in Journal/Newspaper |
Language: | English |
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Cambridge University Press (CUP)
1993
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Online Access: | http://dx.doi.org/10.1017/s0959270900000897 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0959270900000897 |
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crcambridgeupr:10.1017/s0959270900000897 2024-09-15T18:37:21+00:00 Incidental Capture of seabirds by Japanese southern bluefin tuna longline vessels in New Zealand waters, 1988-1992 Murray, T. E. Bartle, J. A. Kalish, S. R. Taylor, P. R. 1993 http://dx.doi.org/10.1017/s0959270900000897 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0959270900000897 en eng Cambridge University Press (CUP) https://www.cambridge.org/core/terms Bird Conservation International volume 3, issue 3, page 181-210 ISSN 0959-2709 1474-0001 journal-article 1993 crcambridgeupr https://doi.org/10.1017/s0959270900000897 2024-08-07T04:04:22Z Summary Fishery observers recorded incidental capture of seabirds during 785 days on Japanese bluefin tuna longline vessels around New Zealand between April and August each year, 1988-1992. High numbers of albatrosses Diomedea spp. and petrels Procellaria spp. were caught on longline hooks during setting and drowned. Twelve seabird taxa were recorded, six of them breeding only in New Zealand. Most were breeding adults, except for Grey-headed and Black-browed Albatrosses. No bias in sex ratio was evident except for Grey Petrels, of which nearly all were female. Winter-breeding species were most often caught. Birds were not caught randomly, but in a highly aggregated fashion suggestive of complex behavioural interactions with the fishery. Most albatrosses were caught by day in the south whereas most petrels were caught by night north-east of New Zealand. Highest capture rates occurred at dawn and dusk off north-east New Zealand in June-August. Very large catches at specific sites contributed disproportionately to the overall catch rate. The estimated minimum number of total seabirds caught in New Zealand waters declined from 3,652 in 1988 to 360 in 1992, probably as a result of mitigation measures introduced progressively by the industry and by government regulation. Use of tori lines to prevent birds seizing baits had an effect, as did setting in total darkness in the south. Considerably more work needs to be done on the development of improved mitigation measures. Greater observer coverage is required to measure accurately the mortality of individual seabird species on tuna longlines throughout the Southern Ocean and to determine the effectiveness of mitigation measures. Article in Journal/Newspaper Southern Ocean Cambridge University Press Bird Conservation International 3 3 181 210 |
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Open Polar |
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Cambridge University Press |
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crcambridgeupr |
language |
English |
description |
Summary Fishery observers recorded incidental capture of seabirds during 785 days on Japanese bluefin tuna longline vessels around New Zealand between April and August each year, 1988-1992. High numbers of albatrosses Diomedea spp. and petrels Procellaria spp. were caught on longline hooks during setting and drowned. Twelve seabird taxa were recorded, six of them breeding only in New Zealand. Most were breeding adults, except for Grey-headed and Black-browed Albatrosses. No bias in sex ratio was evident except for Grey Petrels, of which nearly all were female. Winter-breeding species were most often caught. Birds were not caught randomly, but in a highly aggregated fashion suggestive of complex behavioural interactions with the fishery. Most albatrosses were caught by day in the south whereas most petrels were caught by night north-east of New Zealand. Highest capture rates occurred at dawn and dusk off north-east New Zealand in June-August. Very large catches at specific sites contributed disproportionately to the overall catch rate. The estimated minimum number of total seabirds caught in New Zealand waters declined from 3,652 in 1988 to 360 in 1992, probably as a result of mitigation measures introduced progressively by the industry and by government regulation. Use of tori lines to prevent birds seizing baits had an effect, as did setting in total darkness in the south. Considerably more work needs to be done on the development of improved mitigation measures. Greater observer coverage is required to measure accurately the mortality of individual seabird species on tuna longlines throughout the Southern Ocean and to determine the effectiveness of mitigation measures. |
format |
Article in Journal/Newspaper |
author |
Murray, T. E. Bartle, J. A. Kalish, S. R. Taylor, P. R. |
spellingShingle |
Murray, T. E. Bartle, J. A. Kalish, S. R. Taylor, P. R. Incidental Capture of seabirds by Japanese southern bluefin tuna longline vessels in New Zealand waters, 1988-1992 |
author_facet |
Murray, T. E. Bartle, J. A. Kalish, S. R. Taylor, P. R. |
author_sort |
Murray, T. E. |
title |
Incidental Capture of seabirds by Japanese southern bluefin tuna longline vessels in New Zealand waters, 1988-1992 |
title_short |
Incidental Capture of seabirds by Japanese southern bluefin tuna longline vessels in New Zealand waters, 1988-1992 |
title_full |
Incidental Capture of seabirds by Japanese southern bluefin tuna longline vessels in New Zealand waters, 1988-1992 |
title_fullStr |
Incidental Capture of seabirds by Japanese southern bluefin tuna longline vessels in New Zealand waters, 1988-1992 |
title_full_unstemmed |
Incidental Capture of seabirds by Japanese southern bluefin tuna longline vessels in New Zealand waters, 1988-1992 |
title_sort |
incidental capture of seabirds by japanese southern bluefin tuna longline vessels in new zealand waters, 1988-1992 |
publisher |
Cambridge University Press (CUP) |
publishDate |
1993 |
url |
http://dx.doi.org/10.1017/s0959270900000897 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0959270900000897 |
genre |
Southern Ocean |
genre_facet |
Southern Ocean |
op_source |
Bird Conservation International volume 3, issue 3, page 181-210 ISSN 0959-2709 1474-0001 |
op_rights |
https://www.cambridge.org/core/terms |
op_doi |
https://doi.org/10.1017/s0959270900000897 |
container_title |
Bird Conservation International |
container_volume |
3 |
container_issue |
3 |
container_start_page |
181 |
op_container_end_page |
210 |
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1810481712196485120 |